7
The PCB heating
has two major benefits. Firstly, it warms the board
during winter time (temperatures under -20 C, most circuits have warranty
operation down to -20 C) and secondly it helps to protect the PCB against
humidity when installed outside.
2.1.5 Voice level
10. Voice communication
– the trimmer position is factory and should be
suitable for most installations. Change the trimmer position only when
necessary.
The trimmer "
MIC
" is designed
for microphone volume setting. The
trimmer "
SPK
" is designed for
loudspeaker volume setting.
The volume settings are more
than adequate for most situations.
Therefore we do not recommend
setting the trimmer position more
than ½. The most suitable position
is 1/3 from minimum amplification.
The trimmer "
TRH
" is designed
for
setting
the
microphone
activation level. It allows balancing
between
the
microphone
and
speaker to eliminate feedback. This
setting is also influenced by the noise of the surrounding environment.
Set up Process:
The trimmers MIC and SPK are set to ¼ position from
minimum loudness level (turn fully anti-clockwise for minimum). The trimmer
TRH is set to a central position. To fine tune, make a test call. Speak quietly,
and by adjusting the trimmer TRH from the central position anticlockwise,
your speech should be heard more clearly by the PBX user. The amplification
of the speaker can be adjusted according to your requirements. Voice
interruption might occur if you set the amplification too high. In this case you
can use the trimmer TRH to correct the balance between the speaker and the
microphone.
